Cascade Refrigeration Control for Faster Temperature Stabilization
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Solution Overview
Problem
Dual refrigerating apparatuses face challenges in maintaining consistent cooling temperatures inside storage units due to mismatched compressor specifications and performance variations, leading to longer times for the cascade condenser and storage temperature to reach a constant state.
Innovation Solution
A refrigerating apparatus with separate first and second refrigerant circuits, each with a compressor, condenser, decompressor, and evaporator, along with sensors and controllers to manage compressor operation based on detected temperatures, ensuring the cascade condenser and storage temperature are maintained within predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control is made based on a single sensor detection output for both compressors, then the control system is simple, but the timing and rate of temperature change for the cascade condenser and storage may not match, leading to longer stabilization time
Solution Approach 1:
The control system is segmented into two independent control loops: one controlling the high-temperature side compressor based on cascade condenser temperature, and another controlling the low-temperature side compressor based on storage temperature. This segmentation allows each compressor to be optimized independently, resolving the contradiction between system simplicity and stabilization speed.
Solution Approach 2:
The cascade condenser temperature serves as an intermediary control parameter that bridges the high-temperature side and low-temperature side systems. By controlling the high-temperature side compressor based on cascade condenser temperature rather than directly on storage temperature, the system achieves better coordinated control without excessive complexity.
2Productivity
If compressor specifications are made different to optimize individual performance, then each compressor can operate more efficiently, but the temperatures of the cascade condenser and storage stabilize more slowly
Solution Approach 1:
The control system dynamically adjusts each compressor's operation based on real-time temperature feedback from their respective sensors. The high-temperature side compressor speed is adjusted based on cascade condenser temperature, while the low-temperature side compressor speed is adjusted based on storage temperature, allowing both to operate at optimal efficiency while maintaining coordinated temperature changes.
Solution Approach 2:
The system changes operational parameters (compressor rotation speeds) based on detected temperature conditions. By continuously monitoring cascade condenser temperature and storage temperature separately, the system can independently optimize each compressor's operating parameters to maintain both high efficiency and fast stabilization.
3Productivity
If the evaporation temperature of the high-temperature side evaporator and condensation temperature of the low-temperature side condenser change at different rates, then individual compressor optimization is achieved, but the cascade condenser temperature takes longer to stabilize
Solution Approach 1:
The system implements feedback control for both compressors: the high-temperature side compressor receives feedback from the cascade condenser temperature sensor, and the low-temperature side compressor receives feedback from the storage temperature sensor. This feedback mechanism ensures that temperature changes are coordinated and the cascade condenser stabilizes quickly while maintaining individual compressor optimization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves controllability and reduces the time required for the cascade condenser and storage temperature to stabilize, ensuring efficient and consistent cooling.
Implementation Method 1
an evaporator of the high-temperature side refrigerant circuit (hereinafter referred to as a high-temperature side evaporator) and a condenser of the low-temperature side refrigerant circuit (hereinafter referred to as a low-temperature side condenser) form a cascade condenser so as to mutually exchange heat
Implementation Method 2
a first evaporator, connected circularly with a first piping to form a refrigerating cycle
Implementation Method 3
a second evaporator, connected circularly with a second piping to form a refrigerating cycle
Implementation Method 4
a first condenser, a first decompressor, and a first evaporator, connected circularly with a first piping to form a refrigerating cycle
Implementation Method 5
a second condenser, a second decompressor, and a second evaporator, connected circularly with a second piping to form a refrigerating cycle
Data Source
AI summary
A refrigerating apparatus for keeping an inside of a storage at a predetermined low-temperature state includes first and second refrigerant circuits including compressors, condensers, decompressors, and evaporators, connected circularly with pipings to form refrigerating cycles, the circuit having a first or second refrigerant sealed therein as a working refrigerant, a first sensor which detects a temperature of a cascade condenser constituted by integrating the evaporator of the first refrigerant circuit and the condenser of the second refrigerant circuit in a heat exchangeable manner, first and second controllers which control operation performances of the first and second compressors in a variable manner based on first and second sensor detected temperatures in order that the first and second sensor detected temperatures are first and second temperatures, respectively, and a second sensor which detects a temperature inside the storage.